Sensitivity statistics for instrumental variable estimates — sensitivity

Convenience function that computes robustness values for IV estimates as well as auxiliary first stage and reduced form regressions.

Usage

sensitivity_stats(...)

# S3 method for class 'iv_fit'
sensitivity_stats(model, parm = "iv", q = 1, alpha = 0.05, min = TRUE, ...)

# S3 method for class 'iv.sensemakr'
sensitivity_stats(model, parm = "iv", q = 1, alpha = 0.05, min = TRUE, ...)

Arguments

...: further arguments passed to or from other methods.
model: a model created with the function iv_fit.
parm: contour plots of which estimate? Options are iv for instrumental variable estimates, fs for first-stage estimates, and rf for reduced-form estimates.
q: percent change of the effect estimate that would be deemed problematic. Default is 1, which means a reduction of 100% of the current effect estimate (bring estimate to zero).
alpha: significance level.
min: should we consider biases as large or larger than a certain amount? Default is TRUE.

Value

A data.frame with columns for the estimate, confidence interval bounds (lower and upper), t-value, extreme robustness value (xrv_qa), robustness value (rv_qa), and the parameters used (q, min, alpha, dof).

Examples

data("card")
y <- card$lwage
d <- card$educ
z <- card$nearc4
x <- model.matrix( ~ exper + expersq + black + south + smsa + reg661 + reg662 +
                     reg663 + reg664 + reg665+ reg666 + reg667 + reg668 + smsa66,
                   data = card)
card.fit <- iv_fit(y, d, z, x)

# sensitivity statistics for the IV estimate
sensitivity_stats(card.fit)
#>     estimate        lwr       upr  t.value       xrv_qa       rv_qa q min alpha
#> iv 0.1315038 0.02480484 0.2848236 2.327075 0.0005232443 0.006666407 1   1  0.05
#>     dof
#> iv 2994

# sensitivity statistics for the first-stage
sensitivity_stats(card.fit, parm = "fs")
#>     estimate       lwr       upr t.value      xrv_qa      rv_qa q min alpha
#> fs 0.3198989 0.1476194 0.4921785 3.64085 0.003129076 0.03023129 1   1  0.05
#>     dof
#> fs 2994